Over the last several years, there has been a tremendous growth in data traffic spurred primarily by the World Wide Web/Internet. This growth has resulted in a need for a large amount of bandwidth in the core networks of the Internet.
Optical wavelength division multiplexing networks with terabits of bandwidth per fiber form the back-bone of the current generation of the optical Internet. A dense wavelength division multiplexing (DWDM) system partitions the bandwidth of an optical fiber into multiple channels of data rates in tens of gigabits per second (Gbps), each operating at a distinct wavelength.
FIG. 1 illustrates an optical line system. Wavelengths are multiplexed at one end of the line system 100 and demultiplexed at the other end using what are called end terminals (e.g., 102-1 and 102-2). Wavelengths are selectively added or dropped at intermediate points, using devices called optical add-drop multiplexers or OADMs (e.g., 106-1 and 106-2). As the signal travels over the fiber, the signal loses its power level due to noise and fiber impairments. Optical amplifiers (e.g., 104-1 through 104-4) are placed at the intermediate points between the end terminals to boost the power level of the signal. It is to be understood that an optical line system may include a different number of amplifiers, OADMs, and terminals than are shown in FIG. 1.
Nonetheless, after some point, the quality of the signal gets so degraded that the signal has to be regenerated. This is done by demultiplexing the wavelengths, converting the optical signal to an electrical signal and then back to an optical signal (known as optical-electrical-optical or OEO conversion) using a device called a ring terminal (not expressly shown). A ring terminal is comprised of end terminals placed back to back. Wavelength conversion takes place during this regeneration operation.
Demands for a line system originate (or terminate) at the end terminals or at the OADMs. Each demand requires a wavelength, and multiple demands that go through any common part (segment) of a fiber are allocated or assigned different wavelengths.
Thus, a need exists for line system design systems with effective and efficient routing and bandwidth assignment techniques.